1. Field of Invention
This invention pertains to an apparatus for low voltage control in a residential home. More particularly, this invention pertains to low voltage system with an isolation unit that is easy to install and meets voltage separation requirements.
2. Description of the Related Art
Home automation or management systems which permit increased control of at least some of the electrical subsystems in a dwelling have begun to replace or to supplement conventional wiring systems that operate at a high voltage (typically 120 volts in a residence). These automation systems use low voltage (typically less than 30 volts) circuits controlled by low voltage switches to control high voltage loads. Many home control systems and lighting control systems or subsystems are generally incompatible with conventional wiring techniques. One common complaint is that the additional wiring required for such systems results in a maze of additional wiring. The systems also tend to be relatively expensive. It is desirable, therefore, to have a wiring device that is compatible with existing wiring and requires only the addition of easy to install low voltage wiring during initial construction.
In accordance with the National Electric Code (NEC), electrical conductors including electric light, power, class 1, or non power-limited fire protection signaling conductors must be separated from electrical conductors including power-limited class 2 or class 3 conductors. The conductors of the one group cannot be in any cable, cable tray, compartment, enclosure, outlet box, raceway, or similar fitting with conductors from the other grou
unless the conductors are separated by a barrier. Another exception is where conductors of one group are introduced solely to connect to equipment connected to conductors of the other group.
The NEC further requires that all joints, connections, and splices of electrical cables be made inside an approved enclosure and further must include tight connections with the conduit or cable. Conventional electrical boxes may be made from metal or plastic. The box is further designed with great flexibility so that wires can be brought in from any side by removing a “knock out” to receive a lug for mounting fixtures or the like.
U.S. Pat. Nos. 3,371,149; 3,472,945; 5,445,539; and 6,483,031 are representative of patents disclosing various devices that separate different classes of conductors. U.S. Pat. No. 3,371,149 discloses a metal barrier 26 in a wiring box 11 separating power 22 and television antenna 22a conductors. U.S. Pat. No. 3,472,945 discloses an outlet box 10 divided with a metal barrier plate or partition 15.
U.S. Pat. No. 5,445,539 discloses a wiring device 20 to which different classes of conductors are attached. The wiring device 20 is mounted in a conventional electrical box 84 and separation of the conductors is 25 achieved by routing the low voltage conductors 76 through a tubular projection 32, which extends through a knockout opening 86 in the box 84. The tubular projection 32 is attached to the housing 22 of the wiring device 20, thereby separating the low voltage conductors 76 from the power conductors 48, 80 in the electrical box 84.
U.S. Pat. No. 6,483,031 discloses an enclosure, or control module, 18 attached to an outlet box 58. The low voltage wiring 48 enters the enclosure 18 at the rear, directly from the wall space, and the power wiring 49 enters the outlet box 58, where it is routed to the other end of the enclosure 18, which connects the enclosure 18 to the outlet box 58.
Several problems are typically encountered in the use of low voltage control in a residential home. For example, the low voltage switches are typically push-button switches mounted in the door jamb adjacent a door hinge. Such an installation requires a mortise cut to install the switch, which is a time consuming operation. Also, many low voltage controllers require the use of custom components, such as electrical boxes and cover plates, instead of using standard, readily available components. Further, many low voltage controller installations require that the low voltage wiring be routed in a specific manner, thereby limiting the flexibility of the installer.